It's said that the way to remember vocabulary---or anything, for that matter---is to associate it with something that is personally significant to you. I've elaborated before on my own methods for doing this. Sometimes, however, the associations are made for you. Five years ago I was taking Spanish 3, and had the habit of trying to expand my vocabulary by reading news articles in that language. On September 11, 2001, and in the days following, two words---Torres Gemelas---were permanently embedded in my mind. No matter how infrequently I use them, I will never forget the Spanish words for "twin" and "tower".